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m14 x 0,5 drill

Anyone know what size of tapping drill I would need for the above thread (it's pretty non-standard, and not in my tables), and where to get one?

Thanks

-- Peter Fairbrother

Reply to
Peter Fairbrother
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13.5 should do it.

Mark Rand RTFM

Reply to
Mark Rand

The core diameter (tapping drill size) for any 60 degree thread (metric, UNC/F) is always the o/d minus the pitch so 13.5mm. That is certainly a most unusual thread size though unless it's a typo. 14 x 1.5mm is much more likely.

Reply to
Dave Baker

M14x1 is used for the headstock of some small lathes e.g.Cowells, Unimat 3.

I suspect 13.5 is a bit big, Looking at Tubal Cain's "Drills, Taps and Dies" it would appear that 13.2 would give a 75% engagement.

Measuring some of my Cowells chucks gives me between 12.95 and 13.2. Given that some extrusion might take place I would go for 13.2 if you are using a tap. Possibly a bit less for screw cutting in the lathe.

Reply to
Roger Woollett

What does the tapping drill size for a 14 x 1mm thread have to do with a 14 x 0.5mm one?

Reply to
Dave Baker

Nothing - sorry - must be brain fade.

Reply to
Roger Woollett

I don`t know.I give up.Please tell. :-)

Mark.

Reply to
mark

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